A Coriolis flowmeter is a mass flowmeter utilizing a fact that a Coriolis force acting on a flow tube is proportional to a mass flow rate when the flow tube through which a fluid to be measured flows is supported at both ends thereof and vibration is applied about a support point in a direction perpendicular to a flow direction of the flow tube.
The Coriolis flowmeter is well known and a shape of a flow tube in the Coriolis flowmeter is roughly classified into a straight tube shape and a curved tube shape. When two flow tubes are arranged, manifolds (branching pipes) for branching a channel into two channels are arranged at both end portions of the flow tubes, respectively, corresponding to an inflow port side and an outflow port side.